Electrical condenser



Jan. 27, 1942. w. MANZ ETAL ELECTRICAL: counmusm Filed March so, 1959 2Sheets-Sheet 1 IN VENTORS WALTER MANZ, JO-SEF SCHNIEDERMAIVN, OSKARSCHNE/DER,M/C/AEL WELLI-IOFER, LUDWIG L/NDER, HE/NZ BESSER AN ATTORNEY 2S heets Sheet 2 mvavrogs WALTER MANZ, JOSE/ SCHNIEDERMALNM OSKARSCHNEIDER, MICHAEL WELUIOFFR, wow/a UNDER, I-IE/NZ BESSER AND WILLY V016BY W ATTORNEY I W. MANZ ETAL ELECTRICAL CONDENSER Filed March 30, 1939Jan. 27, 1942.

Patented Jan. 27, 1942 I Walter Manz, Josef Schniedermann, OskarSchneider, Michael Wellhiifer, Ludwig Linder, Heinz Besser, and WillyVoigt, Berlin, Germany, assignors to Fides Gesellschaft fiir dieVerwaltung und Verwertung von gewerbliehen Schutzrechten mitbesohrankter Haftnng, Berlin, Germany, a corporation of GermanyApplication March 30, 1939, Serial No. 264,916

5 Claims.

This invention relates to improved'conde'nsers for use in ultra highfrequency circuits.

Condensers with low self-inductance are required for a great manypurposes and fields in which electrical condensers are employed,especially in connection with means designed to eliminate disturbingactions.

Germany November 24, 1937 To satisfy demands in this regards, speciallywrapped or wound condensers, for instance, condensers with protruding,foil, or folded condensers, or condensers having the electrode stripsinserted at certain points,have been suggested so as to diminish theselirinductance inherent in them. Another step in the-same direction hasbeen to make the connections between the wrapped or rolled condenser andthe terminals bifilar (two-wire) or coaxial or concentric. However, allof these steps prove inadequate whenever the desideratum is to insuremaximum utilization of the true capacity or to shortecircuit ultra-highfrequencies, because the residual inductances in the leads, though low,nevertheless represent a high impedance.

Now, the present invention'discloses ways and means adapted to makecondensers with a selfinductance value that is practically negligiblylow evenfor ultra-high frequencies. The basic and the starting idea hasbeen that, no matter how good the construction of low-inductance leads,the inductance can never be as low as if there were no leads present atall. Hence, the condenser coat is directly united with thecurrentcarrying line or circuit. This means that the branch point wherethe disturbing frequency is branched ofi from the..current-carrying lineis disposed upon the coat of the condenser.

For carrying the solution into practice, there are a number of chanceswhich, for the sake of better understanding, shall first be discussed byreference to the drawings, in which:

Fig. 1 is a fundamental arrangement, illustratirig the principle of thisinvention;

in the prior art, could have the form of a hollow wound or wrappedcondenser, with the line carrying the currentand to be freed fromdisturbing actions beingfpassed through the axis there-. of. It may bementioned at this juncture that the chief application of condensers ofthis kind is where they serve as ducts or lead-ins in a way so that onepole is united with the line to be rid of disturbances, while the otherpole (being preferably joined to the casing) is connected with thegrounded part of the apparatus, say, a metallic wall.v A fundamentalarrangement illustrating the principle of this application is shown inFig. 1. Referring to Fig. 1, suppose 20 is the generator of disturbingactions, while 2| is an apparatus from which disturbances should beprecluded. The line 22 which serves to conduct current between 20 and 2|is brought through the metal wall 24 by way of the bush or wall duct orlead-in condenser 23. The latter which serves the object to rid line 22of disturbing frequencies isunited with one pole of. the line 22 whichis brought through the center of the condenser, whereas the other poleis "united with the casing 25 so that it is connected with the earthedmetal wall 24. Now, thisaction of the condenser 23 will be optimal onlyif there is no inductance berying line, while leads are radicallyprecluded.

Fig. 2 is a cross-section of a practical embodiment of a condenser ofthis invention; Fig. 3 is a schematic showing of the path of currentflow of acondenser shown in Fig. 2;

A practical embodiment of a condenser as here disclosed is shown in Fig.2. 26 is the conductor to be rid of disturbing actions; 2! is a hollow,wrapped or wound condenser comprising coats protruding at the ends. Oneof these coats as indicated at 28 is soldered in itself and alsosoldered together with the conductor 26, while the co-operating coat 29is in direct connection with the casing 30. Merely for the sake'ofgreater clarity of illustration, it is shown in Fig.

2 as being spaced apart from the wrapped condenser 21. A schematicrepresentation of the 'path of current flow through this bushing or ductcondenser is illustrated in Fig. 3, where similar parts (bearing'indexa) are designated by the Fig. 4 is a section of 'a condenser havinganincreased diameter and a decrease" in its thickness; V f

Fig. 5 is a section of a modification of Fig.4; Fig. 6 is a sectionshowing a still further modi iication of Fig. 4'; and Fig. 7 is asection 6! a condenser wherein several units are arrangedin parallel.

same reference numerals as in Fig. 2.

The assumption is made that the .disturbing potential traverses the line26 or 26a from below in the direction of the arrow. 28 or 20a indicatesthe branching point where the disturbing wave flows off by way ofcapacity 2"|, 21a to the casing 7 30, 30a,at the place marked :9, 29,respectively.

In a first embodiment, the condenser, as known This branch point 28, mlies directly on the coat of the condenser 21, 21a so that strayinductance Casing II, a is grounded. As can be seen from Fig. 3, it isnot immaterial at what particular point of the casing the groundconnection is established. But it will be found expedient, at allevents, to provide the grounding exactly at the same level as thebranching point so that the casing serves as a return and that thus theinductance of the condenser coats, fundamentally, is reduced by thebi-iilar or double paths of current flow. The condenser bushing willthus at the most have the inductance of aconductor presenting the sameexternal dimensions as the condenser.

Now, inasmuch as the inductance of a conductor grows in proportion toits length and decreases as its diameter, it wouldappear advantageousaccording to the present invention to make the condenser of as littlelength as feasible, but of the greatest possible diameter, as shown inFig. 4. The breadth b of the wrapped eon denser should be therefore aslittle as feasible in contrast to the diameter of the winding orwrapping d, in other words, theoretically b/d O. It will be understood,of course, that certain limitations are imposed upon this aim inpractice. However, quite apart from that, there arise other factorsimposing a certain limitation upon the ratio b7d. For if the diameterbecomes unduly great, there arises what is called a cross inductanceresulting from the long paths of current from conductor 3| to the lastconvolutions of the wrapper for instance, at the point marked 32.

' In connection with research work resulting-in the evolution of thepresent condenser, in the light of what precedes, it has also been foundthat as a further construction rule that it is advisable to choose theinside diameter of the condenser as large as feasible in order that thethickness of the wrapping (outside radius less inside radius) may bemost favorable in its dimension. In this case, the conductor 'passedthrough the axis of the wrapped condenser does not an up completely theaxial space of the condenser so that, contradistinct from what is trueof Fig. 2, for instance, it.,could not be used as a winding mandrel, forwhich reason it would seem, at first sight, that leads to the coat wouldagain be required. To avoid this, the currentcarrying conductor insidethe condenser is expanded and made tubular, and this tubular part maythen be employed as a winding mandrel.

An embodiment of this idea is shown in Fig. 5. The current-carryingconductor 33 enters into the condenser casing 34, and its tubularexpanded portion I6 is brought through the wrapped condenser 35. Thecurrent from which is to be eliminated a disturbing action is dividedat'the Junction point between conductor 33 and tubular part 3!, and itflows in a way as indicated by the arrows through the tubular part 36.The latter being part and parcel of the currentcarrying conductor willthus be in direct connection with the coat 31 so that again thebranching point 38 for the interference voltage and the signal voltageis located directly at the capacity.

Similarly other embodiments are feasible, and

2,270,953 'in the short-circuit path to ground is avoided.

or draw over a conductor 39, say, a soliddisk, and to solder the twotogether, the circumference of the said disk being united with the coatof the condenser 40. Where suiiiciently high frequencies are dealt with,such an arrangement will prove adequate inasmuch as the radio frequencycurrents will flow around the outside of the disk because of skineffect.

In a special embodiment of a condenser comprising a current-conductinglead or line brought through the interior, for instance, the disk-likeexpansion of the current-carrying conductor or line is first secured onthe coat of the condenser,

whereupon a disc member with a central opening for the cable or the liketo be threaded through is formed to suit such cable gauges as areavailable and in stock. Finally, connection with the cable isestablished by any suitable means, such as soldering. For such anembodiment for which far fewer sizes will have to be kept in stock,there are a number of other ideas which will prove useful in practice.shaped body or structure, that is, the expanded part of thecurrent-carrying conductor or like, could be made in the form of an irisdiaphragm or the like which is adjusted to the cross-section of the lineto be rid of interference or troublesome currents and which then isfixedly connected therewith.

What should also be mentioned is that a con denser bush or duct of thekind hereinbefore described need not necessarily contain merely onewrapped structureyon the contrary, it is possible to provide severalsuch wrapped or wound condensers units arranged in parallel as shown,for instance, in Fig. 7. The conductor 42 to be rid of disturbingactions, traverses the wrapped condenser 43, M, 45; one coat of each ofthese is in direct connection with the conductor 42, while theco-operating coats are brought to the casing 6. This arrangement offersthe additional advantage that residual inductance of the wrapped packetswill be cut down still further as a result of such parallel connection.

This invention should not be limited to the specific modificationsshown, for example, it lies within the scope of this invention toarrangethe condensers between two conductors which are in directconnection withthe condenser coats to free the line of disturbances, also, thecurrentcarrying lead, itself, could be made to form a few turns or loopto serve as a choke coil to provide additional ,reactance.

What is claimed is:

1. A high frequency electric condenser comprising a metallic casinghaving an aperture centrally located at each end thereof, a separateconductor passing through each'one of said apertures, a tubular metallicportion located intermediate each of the ends of said separateconductors and electrically connected thereto, a condenser unitsurrounding said tubular portion, one electrode of said condenser unitconnected to said-tubular portion, the other electrode of the condenserunit connected to said casing.

2. A high frequency electric condenser comprising a metallic casing thelength of which is greater than its height, said metallic casing havingan aperture centrally located at each end thereoL'a separate highfrequency line conductor passing through each one of the apertures ofsaid casing, a tubular metallic portion located intermediate each one ofthe ends of said separate conductor and electrically'connected thereto acondenser unit having one of its electrodes For instance, thediskconnected within said casing to said high frequency conductors, theother condenser electrode connected to the inside wall of said casing.

ing enlarged portions at one end which terminate within said casing todistribute the high 3. A high frequency electric condenser comprising ametallic casing the length of which is I greater than its height, saidmetallic casing having an aperture centrally located at each endthereof, a separate high frequency line conductor passing through eachone of the apertures of said casing, a tubular metallic portion locatedintermediate each one of the ends of said separate conductor andelectrically connected thereto, said high frequency conductors having anenlarged diameter at one end which terminates within said casing todistribute the high frequency current flow therethrough, a condenserunit having one of its electrodesconnected within said casing to theenlarged end of said high frequency conductors, the other condenserelectrode connected to the inside walls of said casing.

4. A high frequencyel-ectric condenser comprising a cylindrical metalliccasing the diameter of which is greater than its length, said metalliccasing having an aperture centrally located at each end thereof, aseparate high frequency line conductor passing through each one of theapertures of said casing, a tubular metallic portion locatedintermediate each of the ends of said separate, conductor andelectrically connected thereto, said high frequency conductors havefrequency current flow therethrough, a condenser unit within saidcasing, said tubular metallic portion serving as a winding mandrel forsaid condenser, one of the condenser electrodes connected within saidcasing tothe enlarged portion of said high frequency conductor, theother condenser electrode connected to the inside of said casing.

5. A high frequency electric condenser comprising a cylindrical metalliccasing, said metallic casing having anaperture centrally located at eachend thereof, a separate high frequency line conductor passing throughthe apertures of said casing, said high frequency conductor having anenlarged diameter spread out to form a hollow disc member, the condenserunit having one of its electrodes connected within said casing to saidhollow disc, the other condenser electrode connectedto the inside wallof said cas-

